Process of manufacturing zinc dust



T. KATO.

PROCESSDF MANUFACTURING ZINC DUST. APPLICATION FILED NOV-26.1919.

ITTY

' Patented Aug. 15, 1922.

TEISUKE KATO, OF I-IYOGO KEN, JAPAN.

PROCESS OF MANI IFACTURING ZINC DUST.

Specification of Letters Patent.

Application filed November 26, 1919. Serial No. 340,928.

To all whom it may concern:

Be it known that I, TEISUKE KATo, subject of Japan, residing at No.2187/1, Maura, Iejima Mura, Shikama Gun, Hyogo Ken, Japan, have inventednew and useful Improvements in a Process of Manufacturing Zinc Dust, ofwhich the following is a specification.

This invention relates to a process of manufacturing zinc dustconsisting in converting metallic zinc or. ores or other materialscontaining metallic zinc or zinc oxide, into zinc vapor by heating thematerial together with a reducing agent by fuel or electricity inafurnace or retort so constructed that it is not exposed to theatmospheric air; diluting the said zinc vapor with a non-oxidizing gas,and settling very fine zinc dust by suddenly cooling the said zincvapor. The object of this invention is to manufacture very fine zincdust in large quantities containing maximum proportions of metalliczinc.

The accompanying drawings show an example of apparatus for carrying myinvention into practice, in which Fig. l is a vertical section, sideview;

Fig. 2, a vertical section, front view, and

Fig. 3, a cross section, plan view.

The same reference numbers refer to the same or corresponding partsthroughout all the figures.

Zinc dust is generally obtained as a byproduct when distilling zincv inretorts; but the density of the zinc vapor in this case be ingcomparatively great and the temperature of the condenser beingcomparatively high, it is possible to obtain only a limited quantity ofzinc dust. Moreover, zinc dust thus obtained is very coarse, part of itoxidized, and the metallic zinc contained therein is comparatively smallin quantity.

The present invention removes the above drawbacks by diluting zinc vaporwith a nonoxidizing gas and cooling it quickly, thus making it possibleto manufacture commercially any desiredamount of zinc dust.

The following is an example of carrying the invention into practice. 1

In the accompanying drawings 1 is a fire grate; 2, a chute for chargingthe furnace with coal; 3 are retorts; and 4; are passages for gaseouszinc volatilized in the retorts, the said passages being cooled by waterjackets. Each retort is provided at one end with a duct 6 for theintroduction of a gas into the retort, and also with a port locatedapproximately at 7 to feed zinc in the form of a rod or the like toreplace volatilized zinc, it being understood that any suitable form ofvalve may be provided for con trolling the dust 6 and a suitable stoppermay also be provided for the port 7; 5 are settling chambers made ofthin plate, having internal partitions and cooled by the air; 8 aresmoke flues, and 9 is an air passage provided between the smoke fluesand opening into the furnace at 10, to heat the air with the heat of thesmoke and thus to cause complete combustion of the gas which rises fromthe grate, thereby to give a greater length to the grate flame. v

To work this apparatus, the retorts are first heated until they becomered. The retorts are then fed with a suitable amount of zinc after whichthe feeding ports are closed, and the temperature gradually raised.-lVhen the temperature in the interior of the furnace'reaches 1000 to1200 C., the zinc contained in the retorts will begin to volatilize.Then, the gas ducts are opened and a non-oxidizing gas, such as carbonmonoxide, nitrogen, acetylene, pure coal 1 gas or the like, introduceinto the retorts so as to dilute the gaseous Zinc to a considerableextent. The gaseous zinc thus diluted is led through the cooled passages4 to the settling chambers 5, where it entirely settles as a very finepowder of metallic zinc. The proportion of the nonoxidizing gas used fordiluting the gaseous zinc is preferably 256 cubic feet at ordinarytemperature for 8 pounds of zinc.

It is to be understood that it is not essential to use the identicalapparatus shown in the accompanying drawings. For heating purpose,electricity may be used, and the settling chamber may be cooled by awater jacket, or the settling of the zinc may be accelerated by theprovision of a cooling pipe. v

In this invention, instead of metallic zinc, zinc ore oxidized byroasting, or any other material containing zinc oxide, may be PatentedAug. 15, 1922.

charged into the retorts together with a reducing agent and zinc may bevolatilized as it is reduced.

Claim: 7 A process of manufacturing zinc dust which consists involatilizing by heat metallic zinc in a retort from which atmosphericair is excluded; diluting the zinc thus

